1. Field of the Invention
The present invention relates to a flap operating device for lowering a flap mounted along a trailing edge of a tapered main wing, while moving the flap rearwards by means of at least two link units which are disposed at a distance from each other in a span direction.
2. Description of the Related Art
Such a flap operating device is known from U.S. Pat. No. 4,444,368. In the flap operating device, a flange link fixed to a leading edge of a flap is supported on a spar through a main link, a first positioning link, a programming link and a second positioning link, so that the flap is lowered while being moved rearwards by swinging the main link by means of an actuator.
In the conventional flap operating device, in general, a plurality of the same link units disposed at distances in the span direction to support the flap, are used and for this reason, the rearwards-protrusion amount of the flap is uniform in the span direction. In a tapered wing with its chord length gradually decreasing from the root toward the tip of the wing, if the rearwards-protrusion amount of the flap is uniform in the span direction, the following problem is encountered: the ratio of the rearwards protrusion amount of the flap protruding rearwards to the chord length is varied in the span direction, and as a result, the aerodynamic characteristic of the flap is not uniform in the span direction. Particularly, in a slotted flap having a slot defined between the main wing and a leading edge of the flap, if an optimal slot width is set on the side of a root, a slot width on the side of a tip is too large, and if an optimal slot width is set on the side of the tip, a slot width on the side of the root is too small. For this reason, it is difficult to sufficiently enhance the aerodynamic characteristic of the flap.
To solve this problem, it is considered that a plurality of flaps separated in the span direction are mounted, and the amounts of protrusion of the flaps are varied in accordance with the chord lengths of the main wing. In this case, however, the number of link units for operating the flap is increased, bringing about in increases in number of parts and in weight. A flap operating device is also known, which is designed so that the flap is guided by a guide rail without use of a link unit or link units. However, if it is intended to avoid that the guide rail interferes with the flap or another structure, there is encountered a problem that the degree of freedom of the design is limited.
Accordingly, it is an object of the present invention to make uniform the aerodynamic characteristic of the flap mounted on a tapered wing in the span direction.
To achieve the above object, according to a first aspect and feature of the present invention, there is provided a flap operating device for lowering a flap mounted along a trailing edge of a tapered main wing while moving the flap rearwards with at least two link units disposed at a distance from each other in the span direction, wherein each of the link units includes a swing arm pivotally supported at one end thereof for vertical swinging movement on an upper portion of a rear spar of the main wing through a first fulcrum pin, a carriage pivotally supported at one end thereof for vertical swinging movement on a lower portion of the rear spar of the main wing through a second fulcrum pin, and a mid-link pivotally supported at one end thereof on an intermediate portion of the swing arm through a third fulcrum pin and at the other end thereof on an intermediate portion of the carriage through a fourth fulcrum pin. A retainer is projectingly mounted at a leading edge of the flap and pivotally supported at its tip end at the other end of the swing arm through a first spherical bearing and a support link is pivotally supported at one end thereof at the other end of the carriage through a second spherical bearing and at the other end thereof at a base end of the retainer through a third spherical bearing. An actuator swings the swing arms through the same angle. The swing arms, the carriages, the mid-links, the retainers and the support links of the link units are disposed in analogous shapes having a predetermined size ratio.
With the above arrangement, each of the at least two link units supporting the flap at the trailing edge of the main tapered wing is comprised of the swing arm, the carriage, the mid-link, the retainer and the support link, and these components are disposed in analogous shapes having the predetermined size ratio. Therefore, when the swing arms of the link units are swung through the same angle by the actuator, the corresponding components of the link units can be swung through the same angle and hence, the flap integral with the retainers can be smoothly moved to protrude. The amount of protrusion of the flap, namely, the amount the retainer moves is determined by the size ratio of the link units and hence, the amount of protrusion of the flap can be changed in the span direction by selecting any size ratio. As a result, the aerodynamic characteristic of the flap can be established freely in each of the portions in the span dire, to thereby contribute to an enhancement in taking-off/landing performances.
When the amount of protrusion of the flap is changed in the span direction, the flap performs a three-dimensional motion such that the flap is moved in the span direction while being moved rearwards and lowered. This three-dimensional motion of the flap can be carried out without hindrance by effecting the interconnection of the swing arm and the retainer, the interconnection of the carriage and the support link and the interconnection of the support link and the retainer through the spherical bearings, respectively. Moreover, the link units are disposed to the rear of the rear spar of the main wing and hence, the link units do not interfere with structures such as a fuel tank and the like disposed in front of the rear spar.
According to a second aspect and feature of the present invention, the size ratio is equal to the ratio between chord lengths of the main wing corresponding to the positions of the link units.
With the above arrangement, the size ratio between the link units formed in the analogous shapes is equal to the ratio between chord lengths of the main wing corresponding to the positions of the link units and therefore, the rearwards-movement amount of the flap can be increased in an area corresponding to the larger chord length of the main wing, and decreased in an area corresponding to the smaller chord length of the main wing. Thus, the flap can be allowed to protrude to an optimal position and through an optimal angle according to the chord length of the main wing at the portions of the main wing in the span direction. Particularly, when the flap is a slotted flap, an appropriate slot width can be ensured at the portions in the span direction.
According to a third aspect and feature of the present invention, the ratio between chord lengths of the flap corresponding to the positions of the link units is equal to the ratio between the chord lengths of the main wing corresponding to the positions of the link units.
With the above arrangement, a ratio of the chord length of the main wing to the chord length of the flap, is uniform in the link units, and a ratio of the chord length of the main wing to the rearwards-movement amount of the flap, is uniform in the link units. Therefore, the aerodynamic characteristic of the flap can be uniform in the portions in the span direction.
According to a fourth aspect and feature of the present invention, there is provided a flap operating device for lowering a flap mounted along a trailing edge of a tapered main wing while moving the flap rearwards with at least two link units disposed at a distance from each other in a span direction, wherein each of the link units includes a swing arm pivotally supported at one end thereof for vertical swinging movement on an upper portion of a rear spar of the main wing through a first fulcrum pin, a carriage pivotally supported at one end thereof for vertical swinging movement on a lower portion of the rear spar of the main wing through a second fulcrum pin, a mid-link pivotally supported at one end thereof on an intermediate portion of the swing arm through a third fulcrum pin and at the other end thereof on an intermediate portion of the carriage through a fourth fulcrum pin. A retainer is projectingly mounted at a leading edge of the flap and pivotally supported at its tip end at the other end of the swing arm through a first spherical bearing, a support link is pivotally supported at one end thereof at the other end of the carriage through a second spherical bearing and at the other end thereof at a base end of the retainer through a third spherical bearing. A drive arm has first and second arm portions extending radially from a pivot, and a push rod is pivotally supported at one end thereof on the second arm portion of the drive arm through a universal joint and at the other end thereof on the intermediate portion of the swing arm through a fourth spherical bearing. The swing arms, the carriages, the mid-links, the retainers and the support links of the link units are disposed in analogous shapes having a size ratio equal to the ratio between chord lengths of the main wing corresponding to positions of the link units. The second arm of the drive arm, the push rod and a portion of the swing arm between the first fulcrum pin and the fourth spherical bearing in each of the link units are disposed in analogous shapes having any size ratio, the first arm portions of the drive arms in the link units being interconnected by a connecting rod. Therefore, the link units are swung through the same angle by an actuator.
With the above arrangement, each of the at least two link units supporting the flap at the trailing edge of the tapered main wing is comprised of the swing arm, the carriage, the mid-link, the retainer, the support link, the drive arm and the push rod, and among these components, the swing arm, the carriage, the mid-link, the retainer and the support link are disposed in analogous shapes having a size ratio equal to the ratio between the chord lengths of the main wing corresponding to the positions of the link units. Therefore, when the swing arms of the link units are swung through the same angle by the actuator, the corresponding components of the link units can be swung through the same angle and hence, the flap integral with the retainer can be moved smoothly to protrude. The amount of protrusion of the flap is varied in a span direction in proportion to the chord lengths of the main wing and hence, the aerodynamic characteristic of the flap can be established freely in each of the portions in the span dire, to thereby contribute to an enhancement in taking-off/landing performances.
In addition, in the link units, the second arm portions of the drive arm and the portions of the swing arm between the first fulcrum pin and the fourth spherical bearing are disposed in analogous shapes having a certain size ratio. Therefore, the swing arms can be swung through the same angle to smoothly operate the flap F by connecting the first arm portions of the drive arms to each other by the connecting rod and swinging the first arm portions through the same angle.
Moreover, the link units are disposed in the rear of the rear spar of the main wing and hence, there is not a possibility that they will interfere with structures such as a fuel tank and the like disposed in front of the rear spar.
According to a fifth aspect and feature of the present invention, when an aerodynamic load is applied to the flap, the connecting rod receives a tensile strength.
With the above arrangement, the connecting rod receives the tensile strength due to the aerodynamic load applied to the flap and hence, even if the connecting rod is formed of a thin and lightweight material, a sufficient strength can be ensured.
The first to fourth ball joints b1 to b4 in an embodiment correspond to the first to fourth spherical bearings of the present invention. A hooke""s joint h in the embodiment corresponds to the universal joint of the present invention. A hydraulic cylinder 31 in the embodiment corresponds to the actuator of the present invention.
The above and other objects, features and advantages of the invention will become apparent from the following description of the preferred embodiment taken in conjunction with the accompanying drawings.